The invention relates to an apparatus for sealably closing a gate valve body or pipe opening which may or may not be under pressure.
Steam powered plants whether they may be nuclear, coal, or oil burning, require periodic overhaul. These plants characteristically include a boiler, piping, and gate valves in the piping. When the movable part of a gate valve is removed from the valve body for refurbishment of the parts the openings in the valve body should be sealed to prevent contamination of the remainder of the system. In the past this sealing operation has been accomplished by O-ring assemblies. These assemblies have not been satisfactory because of the close tolerances which are required to make a strong seal. Out-of-round and pitted interior surfaces of the waterways compound the problem. In some steam powered plants working pressures from 250-300 p.s.i. must be implemented during the overhaul which require a strong and effective seal in the pressure waterway, such as in the gate valve body.